Improve visualisation of model results

[ThomUK]

Currently the model results are visualised using standard functions from the simmer.plot package.
Improve these visualisations to make it simpler to tell the story of the service being modelled.
Keep in mind the need to present the model to:

• Non-technical users who will have no understanding of the DES theory
• Analysts who are more familiar with DES, and who need to be able to understand model performance at a glance.

[ThomUK]

Visualise distributions of model parameters (example from HSMA):

[ThomUK]